The present invention relates to controls for a hydraulically driven vehicle such as a hydraulic pressure type power shovel or the like, wherein the direction of travel is subjected to control by a pair of hydraulic motors arranged in place on the right and on the left sides thereof, respectively.
In conventional practice, controls of this category have usually comprised a pair of independent control levers arranged on the right and on the left and which are connected with a pair of control sections of a hydraulic motor for driving the right and left drive wheels, respectively.
However, in the case of conventional technology of this category, operational control is complicated due mainly to the dual system of control levers; therefore, special skill has been required for the proper operation of such a vehicle.
One object of the present invention rests in providing controls for a hydraulically driven vehicle which are completely capable of eliminating the said operational defects inherent in conventional technology as described heretofore.
Another object of the present invention rests in providing controls for a hydraulically driven vehicle which are completely capable of causing the vehicle to engage in forward movement, rearward movement, a right revolution, and a left revolution. All of this is achieved by the proper actuation of a lever for forward or rearward directional travel and a pair of pedals for additional directional control in a right or left revolution where the pedals are mounted in place on the right and left sides, respectively.
Still other objects of the present invention rest with providing controls for a hydraulically driven vehicle, wherein the lever for forward or rearward directional travel and the pair of pedals for additional directional control mounted in place on the right and left sides respectively, are not in the state of being engaged with each other in mechanical terms but comprise independent operating mechanisms, respectively.
In the present invention, a vehicle can be caused to engage to forward movement and rearward movement, by the proper operation of a lever for that control of travel in a manner effectuating a change-over to that end.
In case either one of the said pair of pedals for right or left directional control is put into operation, while a vehicle still remains in a state of forward movement or rearward movement, a pilot change-over valve for directional control arranged on the side of the respective pedal thus actuated is set at a position for drainage, and the valve for travel (motor control valve) on the side of the pedal thus actuated is set in a neutral position.
Therefore, in the situation where both the lever for forward or rearward directional control of travel and either of the pair of pedals for additional directional control are actuated at the same time, the vehicle is thereby put into a right or left revolution respectively and concurrently.
Since the lever for forward or rearward directional control of travel and the pedals for additional directional control are not engaged with each other in mechanical terms, the operating mechanism for the lever for forward or rearward travel and that for the pedals for right or left directional control can be simplified, respectively, in terms of the constitution thereof; therefore, even in a situation where the lever for forward or rearward travel is changed over for operation in a state wherein the pedals for directional control are actuated, the operating potential thereof is properly kept free from gaining force.
Besides, now that the pilot change-over valve for directional control, wherein the operating potential grows larger than that of the pilot change-over valve, is so designed as to be of the pedal operation system type, the operational properties thereof can be improved in a favorable manner.
Other objects, features and advantages of the present invention will be readily rendered apparent through the following description given in conjunction with the accompanying drawings, wherein FIG. 1 is an explanatory drawing of the diagrammatical consitution of the controls for a hydraulically driven vehicle introduced in the present invention, and FIG. 2 through FIG. 6 are explanatory drawings of the actuation thereof.